Open-Xchange OX Dovecot Pro up to 2.3.0 ManageSieve Service resource consumption

CVSS Meta Temp Score
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CTI Interest Score
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4.9$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as problematic, was found in Open-Xchange OX Dovecot Pro up to 2.3.0. This vulnerability affects unknown code of the component ManageSieve Service. The manipulation results in resource consumption. This vulnerability is identified as CVE-2026-40016. The attack can be executed remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Open-Xchange OX Dovecot Pro up to 2.3.0. Affected is some unknown functionality of the component ManageSieve Service. The manipulation with an unknown input leads to a resource consumption vulnerability. CWE is classifying the issue as CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. This is going to have an impact on availability. CVE summarizes:

Attacker can upload a malicious Sieve script over ManageSieve service (or locally) to bypass configured CPU time limits for Sieve up to 130 times of the configured limit. Attacker can use this to degrade server performance and bypass configured CPU time limits for Sieve scripts. Install fixed version, or alternatively prevent direct access to Sieve scripts via ManageSieve or local access. No publicly available exploits are known.

The advisory is shared for download at documentation.open-xchange.com. This vulnerability is traded as CVE-2026-40016 since 04/08/2026. The exploitability is told to be difficult. It is possible to launch the attack remotely. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

The vulnerability scanner Nessus provides a plugin with the ID 323080 (SUSE SLES16: dovecot24 / dovecot24-backend-mysql / dovecot24-backend-pgsql / etc (SUSE-SU-2026:22185-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (323080) and EUVD (EUVD-2026-29470). Once again VulDB remains the best source for vulnerability data.

Productinfo

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Vendor

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Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.0
VulDB Meta Temp Score: 4.9

VulDB Base Score: 3.1
VulDB Temp Score: 3.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 6.5
NVD Vector: 🔒

CNA Base Score: 5.3
CNA Vector: 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Resource consumption
CWE: CWE-400 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 323080
Nessus Name: SUSE SLES16: dovecot24 / dovecot24-backend-mysql / dovecot24-backend-pgsql / etc (SUSE-SU-2026:22185-1)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Timelineinfo

04/08/2026 CVE reserved
05/12/2026 +34 days Advisory disclosed
05/12/2026 +0 days VulDB entry created
06/27/2026 +46 days VulDB entry last update

Sourcesinfo

Vendor: open-xchange.com

Advisory: adv-2026-0002
Status: Confirmed

CVE: CVE-2026-40016 (🔒)
GCVE (CVE): GCVE-0-2026-40016
GCVE (VulDB): GCVE-100-363036
EUVD: 🔒

Entryinfo

Created: 05/12/2026 17:05
Updated: 06/27/2026 21:29
Changes: 05/12/2026 17:05 (64), 05/12/2026 17:59 (1), 05/19/2026 02:57 (11), 06/27/2026 21:29 (2)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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